My truck starts OK with out the glow plugs down to about 50. Below that it gets cranky. Using the glow plugs cures that. Even on warmer days the glow plugs help smooth out the idle right after starting. Plugging is great if you can. My truck is track/trailer queen. I tow it to pulls sometimes a days drive away. So I would need lots of extension cords to keep it plugged in.It has been as cold as in the 30s and with the glow plugs it fires right up.
What kind of compression ratio do you run, John?